Curable composition comprising adhesion improver

ABSTRACT

An adhesion-improver which comprises a reaction product of an amino compound having a primary and/or secondary amino group in the molecule or a modified amino compound obtained by modifying the amino compound with a compound having an epoxy group, and a carbonyl compound, particularly a dicarbonyl compound of the formula ##STR1## wherein R 1  and R 2  are the same or different and are each an alkyl having 1 to 16 carbon atoms, an aryl having 6 to 12 carbon atoms or an alkoxy having 1 to 4 carbon atoms, R 3  is a hydrocarbon group having one or more carbon atoms, and n is 0 or 1, is used to prepare a curable composition such as an adhesive, sealing agent, paint or pourable compound.

This application is a division of Ser. No. 06/836,301, filed Mar. 5,1986, now U.S. Pat. No. 4,981,987.

The present invention relates to an adhesion-improver, more particularlyto an adhesion-improver which is an addtive for improving the adhesionof a curable composition to a substrate.

PRIOR ART

Conventional curable compositions such as adhesives, sealing agents,paints, pourable compounds, etc. are usually composed of various resinsor synthetic rubbers as a main component. In addition to the maincomponent, i.e. resins and rubbers, the curable compositions are usuallyincorporated with filling agents, plasticizers, solvents, dyes andpigments, flow control agents, and further adhesion-improvers in orderto improve the adhesion or bonding properties of the composition to asubstrate.

For the purpose of the improvement of adhesion of curable compositionsto the substrate, it has been practized to incorporate a small amount ofphenol resins, petroleum resins, epoxy resins, silane coupling agents,titanate coupling agents, and the like. It has also been practiced topreviously apply a primer to the substrate in order to improve theadhesion of the curable composition to the substrate.

However, the conventional adhesion-improvers could not improvesufficiently the adhesion after curing of the curable composition, andhence, it has been desired to find a new adhesion-improver. Besides, itis desired to eliminate such an additional step for applying a primerbefore the application of a curable composition in view of labor-saving.

OBJECT OF THE INVENTION

Under the above situation, the present inventors have intensivelystudied an improved adhesion-improver which is useful for improvingadhesion of curable compositions. The inventors had firstly found that areaction product of a hydrolyzable alkoxysilane compound having aprimary and/or secondary amino group and a carbonyl compound iseffective as an adhesion-improver, but as a result of further intensivestudy, hey have now found that a dehydration condensation reactionproduct of a specific amino compound and a stoichiometrically equivalentor excess amount of a specific carbonyl compound is particularlyexcellent as an adhesion-improver for curable compositions.

An object of the invention is to provide a novel adhesion-improversuitable for curable compositions. Another object of the invention is toprovide an improved curable composition having improved adhesion andcuring characteristics. These and other objects and advantages of theinvention will be apparent to persons skilled in the art from thefollowing description.

DETAILED DESCRIPTION

The adhesion-improver of the invention comprises a reaction product ofan amino compound having a primary and/or secondary amino group in themolecule and a carbonyl compound of the formula: ##STR2## wherein R¹ andR² are the same or different and are each an alkyl group having 1 to 16carbon atoms (e.g. methyl, ethyl, propyl, butyl, heptyl, hexyl, octyl,nonyl, decyl, undecyl, hexadecyl, etc.), an aryl group having 6 to 12carbon atoms (e.g. phenyl, tolyl, xylyl, naphthyl, etc.) or an alkoxygroup having 1 to 4 carbon atoms (e.g. methoxy, ethoxy, propoxy, butoxy,etc.), R³ is a hydrocarbon group having one or more carbon atoms, suchas a straight or branched chain alkylene having 1 to 5 carbon atoms(e.g. methylene, ethylene, propylene, isopropylene, etc.), an alkenylenehaving 2 to 5 carbon atoms (e.g. vinylene, propenylene, etc.), anarylene having 6 carbon atoms (e.g. 1,4-phenylene), and n is 0 or 1.

The amino compound to be reacted with the carbonyl compound may be amodified amino compound, for instance, a reaction product or a mixtureof an amino compound having a primary and/or secondary amino group andan epoxyalkyl-alkoxysilane compound, or a reaction product or a mixtureof an aminoalkylalkoxysilane compound and a compound having an epoxygroup.

The amino compound having a primary and/or secondary amino group used inthe present invention includes, for instance, aliphatic amines, such asmono-and/or dialkylamines having 1 to 10 carbon atoms in each alkylmoiety (e.g. isopropylamine, diisopropylamine, diethylamine,propylamine, monoallylamine, diallylamine, isobutylamine,sec-butylamine, 2-ethylhexylamine, etc.), mono- or dialkylaminoalkylamines having 1 to 10 carbon atoms in each alkyl moiety (e.g.dimethylaminopropylamine, diethylaminopropylamine,monomethylaminopropylamine, etc.), alkoxyalkylamines having 1 to 10carbon atoms in the alkoxy moiety and 1 to 10 carbon atoms in the alkylmoiety (e.g. 3-(2-ethylhexyloxy)propylamine, 3-ethoxypropylamine,3-methoxypropylamine, etc.), alkanolamines having 1 to 10 carbon atoms(e.g. isopropanolamine, ethanolamine, etc.), iminonitriles (e.g.iminodipropionitrile, etc.), acetamides (e.g. thioacetamide, etc.),iminoamines (e.g. methyliminobispropylamine, etc.), aliphatic diamines(e.g. diaminopropane, hexamethylenediamine, ethylenediamine,propylenediamine, butylenediamine, triglycoldiamine,N,N'-diisobutyl-trimethylhexamethylenediamine, etc.), aliphatictriamines (e.g. diethylenetriamine, etc.), aminoalkyl ethers (e.g.di-β-aminoethyl ether, di-γ-amino-n-propyl ether, etc.),aminoalkylsulfides (e.g. di-β-aminoethylsulfide,di-β-aminoethyldisulfide, etc.); alicyclic amines having 6 to 20 carbonatoms, such as mono- or dicycloalkylamines having 6 to 10 carbon atomsin each cycloalkyl moiety (e.g. dicyclohexylamine, cyclohexylamine,etc.), cycloalkyl-diamines having 6 to 10 carbon atoms in eachcycloalkyl moiety (e.g. 1,8-p-methanediamine, isophoronediamine,diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine),1,3-bisaminomethylcyclohexane,3-aminomethyl-3,3,5-trimethyl-cyclohexylamine,N,N'-diisobutylisophorone-diamine, etc.); aromatic amines, such as mono-or diphenylalkylamines having 1 to 3 carbon atoms in the alkyl moiety(e.g. dibenzylamine, etc.), aminobenzoic acids (e.g. p-aminobenzoicacid, etc.), aryldiamines (e.g. phenylenediamine, xylylenediamine,dianisidine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane,etc.), aminoaryl ethers (e.g. 4,4'-diaminodiphenyl ether, etc.),arylenediamines (e.g. phenylenediamine, etc.), aryltriamines (e.g.triaminoxylene, etc.); piperazine compounds (e.g.N-aminoethylpiperazine, 3-(3-aminopropyl)-3,2-dimethylpiperazine,1-(2-hydroxyethyl)-piperazine, etc.); and further; polyamidoamines;polyoxyalkylene ether amines; amine-modified butadiene homo-orcopolymers; polyethyleneimines, and the like. An aminoalkylalkoxysilanecompounds as mentioned hereinafter are also used as the amino compound.Preferred amino compounds are compounds having a large molecular weightand polymers. Particularly suitable examples of the amino compounds areaminoalkylalkoxysilanes, cycloalkyldiamines, polyamidoamines,polyoxyalkylene ether amines and amino-modified butadiene homo- orcopolymers. These amino compounds may be used alone or in combination oftwo or more thereof. The amino compounds may also be modified with aspecific compound as mentioned below.

The modified amino compound includes a reaction product of the aminocompound as mentioned above and an epoxyalkylalkoxysilane compound or amixture of the reaction product and the amino compound. Theepoxyalkylalkoxysilane compound includes, for instance,γ-glycidoxypropyldimethyl-ethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethylmethyl-dimethoxysilane,β-(3,4-epoxycyclohexyl)ethylmethyl-dimethoxysilane, and the like. Thereaction of the amino compound and the epoxyalkylalkoxysilane compoundis carried out by heating with agitation. The reaction product shouldhave one or more primary and/or secondary amino groups in the molecule.

When the amino compound used in the present invention is anaminoalkylalkoxysilane compound, the modified amino compound is areaction product of the aminoalkylalkoxysilane compound and a compoundhaving an epoxy group (e.g. an epoxy resin) or a mixture of the reactionproduct and the amino compound.

The aminoalkylalkoxysilane compound includes, for instance,N-(β-aminoethyl)aminomethyltrimethoxysilane,γ-aminopropyltriethoxysilane, aminopropyltriethoxysilane,γ-aminopropylmethyldiethoxy-silane,N-(β-aminoethyl)-γ-aminopropyltriethoxysilane,N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, and the like. Themodified amino compound should retain at least a part of the primaryand/or secondary amino group in the molecule. The epoxy resin used asthe compound having epoxy group is a glycidyl ether type epoxy resin,for instance, a reaction product of a polyvalent phenol andepichlorohydrin [e.g. diglycidyl ether of 2,2-bis(4-hydroxyphenylpropane(referred to as "bisphenol A")], a reaction of an alkylene oxide adductof a polyvalent phenol and epichlorohydrin [e.g. diglycidyl ether ofbisphenol A ethylene oxide adduct and optionally bisphenol A propyleneoxide adduct], a reaction product of an aliphatic polyvalent alcohol andepichlorohydrin [e.g. triglycidyl ether of glycerin, or diglycidyl etherof 1,6-hexanediol], a hydrated product of a reaction product of apolyvalent phenol and epichlorohydrin [e.g. a polyglycidyl ether ofhydrated bisphenol A], alicyclic epoxy resins, novalac epoxy resins,glycidyl ester type epoxy resins, and the like. Particularly suitableexample is diglycidyl ether of a polyvalent phenol (e.g. bisphenol A).The epoxy resins have preferably an epoxy equivalent of not more than500 and are preferably liquid at room temperature.

The carbonyl compound of the above-mentioned formula: ##STR3## whereinR¹, R², R³ and n are as defined above includes, for instance, ethylpyruvate, dimethyl maleate, acetylacetone, propionylacetone, an alkyl(C₁ -C₅) methyl diketone (e.g. dimethyl diketone, ethyl methyldiketone), an alkyl (C₁ -C₄) acetacetate (e.g. methyl acetacetate, ethylacetacetate), dialkyl (C₁ -C₄) malonae (e.g. dimethyl malonate, diethylmalonate, methyl ethyl malonate), dibenzoylmethane, and the like. Amongthese, dicarbonyl compounds having active methylene group arepreferable.

When modified amino compounds as mentioned above are used as the aminocompound to be reacted with a carbonyl compound, other carbonylcompounds than the above dicarbonyl compounds as mentioned above canalso be used. The other carbonyl compounds include, for instance,aldehydes (e.g. acetaldehyde, propionaldehyde, n-butyraldehyde,isobutyraldehyde, diethylacetaldehyde, glyoxal, benzaldehyde, etc.),cyclic ketones (e.g. cyclopentanone, trimethylcyclo-pentanone,cyclohexanone, trimethylcyclohexanone, etc.), aliphatic ketones (e.g.acetone, methyl ethyl ketone, methyl propyl ketone, methyl isopropylketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone,diisopropyl ketone, dibutyl ketone, diisobutyl ketone, etc.), and thelike.

The reaction of the amino compound and the carbonyl compound is carriedout under the same conditions as in the conventional dehydrationcondensation reaction of an amine and an aldehyde or ketone. Forinstance, both compounds are reacted by reacting with reflux in thepresence of a moisture absorbent while removing produced moisture. Morespecifically, an amino compound is reacted with a stoichiometricallyequivalent or excess amount of a carbonyl compound (in case ofdicarbonyl compound, one of the two keto groups being reacted) in anappropriate organic solvent (e.g. toluene, xylene, benzene) in thepresence of a moisture absorbent (e.g. molecular sieves, anhydrousmagnesium sulfate) at a temperature of room temperature or elevatedtemperature (e.g. 30° C. to 80° C.) with agitation.

The reaction products wherein the amino group in the amino compound isblocked with the carbonyl compound is used alone or in combination oftwo or more kinds thereof for the incorporation into a curablecomposition.

The curable composition of the present invention comprises as a maincomponent a polyurethane resin, an epoxy resin, a silicone, a modifiedsilicone, a polyvinyl chloride resin, an acrylic resin, a phenol resin,a polyester resin, a polysulfide resin or a curable liquid rubber. Theadhesion-improver of the present invention, i.e. the reaction product ofan amino compound and a carbonyl compound as mentioned above, is usuallyincorporated into the curable composition in an amount of 0.05 to 10parts by weight, preferably 0.1 to 5.0 parts by weight, to 100 parts byweight of whole weight of the curable composition. By the incorporationof the adhesion-improver of the present invention, the curablecomposition shows improved adhesion to the substrate (e.g. metals,painted metals, plastics, glass, inorganic substances, woodensubstrates, etc.). The adhesion-improver of the present invention canalso improve the curing characteristics (e.g. curing rate, set-upcharacteristics) of the curable composition. Besides, by theincorporation of the adhesion-improver of the present invention, thecurable composition can directly be applied to the substrate withoutprevious application of any primer which is required for theconventional curable compositions. When the adhesion-improver of thepresent invention is used in an amount of less than 0.05 part by weightto 100 parts by weight of the curable composition, the desiredimprovement of adhesion of the curable composition is insufficient, andon the other hand, when the amount is over 10 parts by weight, thecuring characteristics of the composition is undesirably inhibited.

The curable composition may also be incorporated with other conventionaladditives, such as filling agents, plasticizers, solvents, catalysts,antioxidants, pigments, and the like.

The present invention is illustrated by the following Examples butshould not be construed to be limited thereto.

EXAMPLE 1

3-(2-Ethylhexyloxy)propylamine (18.7 parts by weight), anhydrous toluene(86.1 parts by weight) and molecular Sieves (as a moisture absorbent, 10parts by weight) are charged into a reactor wherein air is replaced withdry nitrogen gas. To the mixture is gradually added acetylacetone (10.0parts by weight) at room temperature with agitation. After the addition,the mixture is reacted with agitation at room temperature for 4 hours.After completion of the reaction, the moisture absorbent is filtered offby suction to give an adhesion-improver.

The adhesion-improver obtained above (1.0 part by weight) is added to acurable composition [one-pack type moisture curing polyurethane adhesive(Penguin Cement 930®, manufactured by Sunstar Giken K.K., Japan), 100parts by weight] to give the desired curable composition.

The curable composition thus prepared was subjected to the followingtest.

The curable composition was applied for the adhesion of a plywood and analuminum plate, which was cured at 5° C. for 24 hours. The test samplethus prepared was subjected to a peel test under the conditions ofatmosphere of 20° C. and 65% relative humidity, at an angle of 180° at acrosshead speed of 200 mm with Autograph IM-500. As a result, it showeda peel strength of 4.5 kg/25 mm, and the state of break of the testsample was material break, which means that the test sample showedexcellent adhesion. As a reference, the same starting curablecomposition as used above without incorporation of the adhesion-improverwas tested likewise. As a result, it showed a peel strength of 1.8 kg/25mm, and the sample was broken at interface, which means that theadhesion was very weak.

EXAMPLE 2

In the same manner as described in Example 1, 1,8-p-methanediamine (17.0parts by weight) and dimethyl malonate (26.4 parts by weight) aresubjected to dehydration condensation reaction to give anadhesion-improver.

The adhesion-improver obtained above 91.0 part by weight) is added tothe adhesive component (100 parts by weight) of two-pack typepolysulfide sealing agent (Betaseel #169-4®, manufactured by SunstarGiken K.K., Japan) to give the desired curable composition.

The curable composition obtained above was subjected to the followingtest.

The curable composition (100 parts by weight) was mixed with a curingcomponent (10 parts by weight) of the above two-pack type polysulfidesealing agent, and the mixture was applied for the adhesion of stainlesssteel plates by bead sealing, and it was cured at 20° C. for 7 days.Thereafter, it was subjected to a peel test by hand. As a result, thestate of break was material break, which means that the test sampleshowed excellent adhesion. Thus, the curable composition can be appliedwithout previous application of a primer. As a reference, the samesealing agent as used above was tested likewise without using anyadhesion-improver of the present invention. As a result, it was brokenat interface.

EXAMPLE 3

An epoxy resin (Epicote 828®, manufactured by Yuka Shell Epoxy Co.,Japan, 22.8 parts by weight) and γ-amino-propyltriethoxysilane (22.1parts by weight) are reacted at 50° C. for 24 hours. The reactionproduct or a mixture of the above reactants (totally 44.9 parts byweight) is reacted with cyclohexanone (9.8 parts by weight) in the samemanner as described in Example 1 to give an adhesion-improver.

The adhesion-improver obtained above (2.5 parts by weight) is added to amoisture curing polyurethane sealing agent (Penguin Seal #955®,manufactured by Sunstar Giken K.K., Japan, 100 parts by weight) toprepare the desired curable composition.

The curable composition thus prepared was subjected to the followingtest.

The curable composition was applied for the adhesion of aluminum platesby bead sealing, which was cured at 20° C. for 7 days. The test samplethus prepared was subjected to a peel test by hand at room temperature.As a result, the state of break of the test sample was material break,which means that the adhesion was very strong, and there was obtainedthe same adhesion effect as the case a primer was previously applied tothe substrate to be adhered. As a reference, the same sealing agent asused above without incorporation of the adhesion-improver was testedlikewise. As a result, the sample was broken at interface.

EXAMPLE 4

An epoxy resin (Epicote #828®22.8 parts by weight) andγ-(2-aminoethyl)aminopropyltrimethoxysilane are reacted at 50° C. for 24hours. The reaction product or a mixture of the above components(totally 45.0 parts by weight) is reacted with acetylacetone (20.0 partsby weight) in the same manner as described in Example 1 to give anadhesion-improver.

The adhesion-improver obtained above (1.0 part by weight) is added to amoisture curing silicone sealing agent (Penguin Seal 2505®, manufacturedby Sunstar Giken K.K., Japan, 100 parts by weight) to prepare thedesired curable composition.

The curable composition obtained above was subjected to the followingtest.

The curable composition was applied for the adhesion of polyvinylchloride plates by bead sealing, which was cured at 20° C. for 7 days.Thereafter, it was subjected to a peel test by hand. As a result, thestate of break was material break, which means that the test sampleshowed excellent adhesion.

EXAMPLE 5

A polyamide resin (Tomide 225-X®, manufactured by Fuji Kasei K.K.,Japan, 35.0 parts by weight) and γ-glycidoxypropyltrimethoxysilane (47.2parts by weight) are reacted at 50° C. for one day to give a modifiedamino compound. The modified amino compound thus obtained (82.2 parts byweight) is reacted with ethyl acetacetate (26.0 parts by weight) in thesame manner as described in Example 1 to give an adhesion-improver.

The adhesion-improver obtained above (1.5 part by weight) is added to amoisture curing polyurethane adhesive (Penguin Cement 930®, manufacturedby Sunstar Giken K.K., Japan, 100 parts by weight) to prepare a curablecomposition.

The curable composition was subjected to a peel test in the same manneras described in Example 1. As a result, it showed a peel strength of 49kg/25 mm, and the state of break was material break. The curablecomposition was excellent both in the curing characteristics andadhesion.

EXAMPLE 6

A polyoxypropylenediamine (Jeffermin D400®, manufactured by Texaco Chem.Co., 20.0 parts by weight) is reacted withγ-glycidoxypropyltrimethoxysilane (47.2 parts by weight) at 50° C. forone day to give a modified amino compound. The modified amino compoundthus obtained (67.2 parts by weight) is reacted with methyl isobutylketone (20.0 parts by weight) in the same manner as described in Example1 to given an adhesion-improver.

The adhesion-improver thus obtained (3 parts by weight) is added to areduction component (100 parts by weight) of a Redox type acrylicadhesive (Tuff Lock 6201®, manufactured by Sunstar Giken K.K., Japan) togive a curable composition.

The curable composition obtained above was subjected to the followingtest.

The curable composition (the reduction component, 100 parts by weight)was mixed with an oxidizing component (10 parts by weight) of the aboveRedox type acrylic adhesive, and the mixture was applied for theadhesion of a steel plate and a plastic plate and both plates wereadhered overlapping in a length of 25 mm. The test piece thus preparedwas kept at room temperature for one day in order to cure the adhesive,and then it was subjected to a test of an adhesive strength under shear.As a result, it showed a strength of 250 kg/cm². As a reference, thesame adhesive as used above was tested likewise without using anyadhesion-improver of the present invention. As a result, it showed aadhesive strength under shear of 220 kg/cm².

What is claimed is:
 1. A curable composition, which comprises a maincomponent selected from the group consisting of a polyurethane resin, anepoxy resin, a silicone, a modified silicone, a polyvinyl chlorideresin, an acrylic resin, a phenolic resin, a polyester resin, apolysulfide resin and a curable liquid rubber andan adhesion-improver,which comprises a reaction product of an amino compound having a primaryand/or a secondary amino group in the molecule and a carbonyl compoundof the formula: ##STR4## wherein R¹ and R² are the same or different andare each an alkyl having 1 to 16 carbon atoms or an alkoxy having 1 to 4carbon atoms, said amino compound being a member selected from the groupconsisting of an alkoxyalkylamine having 1 to 10 carbon atoms in thealkoxy moiety and 1 to 10 carbon atoms in the alkyl moiety; acycloalkyldiamine having 6 to 10 carbon atoms in the cycloalkyl moiety;selected from polyamidoamines and polyoxyalkylene ether amines and anepoxyalkylalkoxysilane compound selected fromα-glycidoxypropyldimethylethoxysilane,α-glycidoxypropylmethyldiethoxysilane,α-glycidoxypropyltrimethoxysilane,B-3,4-epoxycyclohexyl)-ethyltrimethoxysilane, andB-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane; and a reactionproduct or a mixture of an aminoalkylalkoxysilane compound selected fromN-(B-aminoethyl)aminomethyltrimethoxysilane,α-aminopropyltriethoxysilane, α-aminopropylmethyldiethoxysilane,N-(B-aminoethyl)-α-aminopropyltrimethoxysilane,N-(B-aminoethyl)-α-aminopropyltriethoxysilane, andN-(B-aminoethyl)-α-aminopropylmethyldimethoxysilane and a compoundhaving an epoxy group selected from diglycidyl ether of bisphenol A,diglycidyl ether of bisphenol A ethylene oxide adduct, triglycidyl etherof glycerin, diglycidyl ether of 1,6-hexanediol, and a polyglydicylether of hydrated bisphenol A.
 2. The composition according to claim 1,wherein the amino compound having a primary and/or secondary amino groupin the molecule is a reaction product or a mixture of an amino compoundand an epoxyalkylalkoxysilane compound.
 3. The composition according toclaim 1, wherein the amino compound having a primary and/or secondaryamino group in the molecule is a reaction product or a mixture of anaminoalkylalkoxysilane and a compound having an epoxy group.
 4. Acurable composition, which comprises a main component selected from thegroup consisting of a polyurethane resin, an epoxy resin, a silicone, amodified silicone, a polyvinyl chloride resin, an acrylic resin, aphenol resin, a polyester resin, a polysulfide resin and a curableliquid rubber, and an adhesion-improver, which comprises a reactionproduct of a carbonyl compound selected from the group consisting of acompound of the formula: ##STR5## wherein R¹ and R² are as defined inclaim 1; a cyclic ketone selected from cyclopentanone,trimethylcyclopentanone, cyclohexanone, and trimethylcyclohexanone; andan aliphatic ketone selected from acetone, methyl ethyl ketone, methylpropyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, diethylketone, dipropyl ketone, diisopropyl ketone, dibutyl ketone, anddiisobutyl ketone with an amino compound selected from the reactionproduct or the mixture of an amino compound selected frompolyamidoamines and polyoxyalkylene ether amines and anepoxyalkylalkoxysilane compound as set forth in claim 6 and the reactionproduct or the mixture of an aminoalkylalkoxysilane compound and acompound having an epoxy group as set forth in claim 1.